Light source device including phase matching element for measuring the degree of oxygen saturation in blood

Abstract

This light source device includes one light emission unit from which light is emitted, plural light source units, a photo coupler, and a control unit. The plural light source units output outgoing lights with mutually differing wavelengths. The photo coupler connects the light emission unit and plural light source units. The control unit controls the plural light source units via a driver. Each of the plural light source units includes a light emitting element and a wavelength conversion unit. The wavelength conversion unit converts the wavelength of light output from the light emitting element, thus generating the outgoing light.

The invention claimed is: 
     
       1. A light source device, comprising:
 one light emission unit from which light is emitted; 
 a plurality of light source units that output outgoing light with mutually differing wavelengths; 
 a photo coupler that connects the light emission unit and plurality of light source units; and 
 a controller that controls the plurality of light source units, wherein each of the plurality of light source units includes: 
 a light emitting element; 
 a wavelength conversion unit, including a phase matching element, that converts a wavelength of light output from the light emitting element, thus generating the outgoing light; and 
 a detection unit that detects an intensity of reflected light generated by light emitted from the light emission unit being reflected by a measurement target, wherein 
 the controller gradually increases the output of each light emitting element, and stops the increase of the output of each light emitting element when the intensity of the reflected light detected by the detection unit reaches a threshold value or above; 
 wherein the threshold value is based on a degree of oxygen saturation in blood; and 
 wherein the controller is configured to modulate respective drive currents to modulate respective intensities of simultaneously outgoing light of at least two light emitting elements, and to measure a signal corresponding to the outgoing light intensities at a light receiving side of the detection unit using a fundamental wave drive current as a reference signal. 
 
     
     
       2. The light source device according to  claim 1 , wherein
 the controller causes at least two of the light source units to operate simultaneously, thus causing at least two kinds of the outgoing light to be emitted simultaneously from the light emission unit. 
 
     
     
       3. The light source device according to  claim 1 , wherein light emitted from the light emission unit is used as a light source for measuring a saturated oxygen concentration of blood. 
     
     
       4. The light source device according to  claim 3 , wherein the wavelengths of the outgoing lights output by the plurality of light source units are 490 nm or more, 630 nm or less. 
     
     
       5. The light source device according to  claim 2 , wherein light emitted from the light emission unit is used as a light source for measuring a saturated oxygen concentration of blood. 
     
     
       6. The light source device according to  claim 1 , wherein the wavelengths of the outgoing lights output by the plurality of light source units are 490 nm or more, 630 nm or less. 
     
     
       7. The light source device of  claim 1 , wherein the controller is further configured to change modulated respective frequencies of the outgoing light, and based on detecting the modulated respective frequencies separately at the light receiving side by the detection unit, independently measure an intensity of light of each of the differing wavelengths.